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Plant Protection Today - Combatting Navel Orangeworm

Combatting Navel Orangeworm
August 8, 2018

PPQ Delivers Sterile Insects to Help Protect California Tree Nuts

By Heather Curlett

The invasive navel orangeworm continues to damage—at rising levels—California’s $6 billion pistachio and almond crops. The tree nut industry is calling for new and improved tools to fight back against this harmful pest. USDA’s Plant Protection and Quarantine (PPQ) program is answering that call.

For the last two and half years, PPQ scientists have been adapting sterile insect technology—a tool they have been successfully using to help eliminate pink bollworm from the United States—to rear and sterilize navel orangeworm moths. PPQ and the tree nut industry believe this technology may also help protect at-risk pistachio and almond orchards in California.

How Sterile Insects Helped Knock Back Pink Bollworm

Pink bollworm is one of the most destructive cotton pests in the world. It was first detected in the United States in 1917 and quickly spread throughout U.S. cotton-growing States. Instead of spraying conventional insecticides, PPQ and its partners agreed to use an integrated, non-chemical approach to eliminating pink bollworm. The approach included planting transgenic cotton, using insect pheromones to disrupt mating, and releasing sterile insects to prevent reproduction.

“At the height of the program, we were distributing more than 5 million moths per day in California alone, and more than 30 million across all impacted States,” said Eoin Davis, Pink Bollworm Rearing Facility Director. “Initially our goal was simply to prevent the spread of this pest. But over time, we saw how effective this technique was, and we realized that it could help us eradicate pink bollworm.”

Thanks to cutting-edge tools like sterile insect technique, the United States is on the verge of declaring U.S. commercial cotton-growing areas free of pink bollworm. [Photo courtesy of Peggy Greb, USDA Agricultural Research Service,]

Pivoting from One Pest to the Next

With funding from the pistachio industry, PPQ has been developing methods for mass rearing and sterilizing navel orangeworm moths. In less than three years, they have ramped up production to 1 million sterile moths per day at the Pink Bollworm Rearing Facility.

“This year, we are shipping sterile moths from Phoenix to California, where the California Department of Agriculture and the pistachio industry will test the release process and conduct trial field releases in isolated almond and pistachio groves in the San Joaquin Valley,” said USDA National Policy Manager Karen Maguylo. “Over the next two years, we will evaluate the impact on navel orangeworm populations in the test area.”

The California Department of Agriculture and the California tree nut industry release sterile navel orangeworm moths over a remote test area in the San Joaquin Valley.

These releases are a testament to what can be achieved when industry, state government, and PPQ work together. As a result of their effective collaboration, California agriculture officials and the pistachio industry are carrying out these trials years sooner than expected. The pistachio industry plans to continue funding field trials through 2020, with the hope that these sterile insects will help protect at-risk almond and pistachio production from further navel orangeworm damage.

“Sterile insects aren’t a silver bullet,” said Maguylo, “but they will complement other area-wide control measures, including sanitation, mating disruption, and coordinated pesticide applications to help sustain effective, long-term pest management.”
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